The word sceptic denotes a member of one of the ancient Greek schools of philosophy, or more specifically that of Pyrrho, who believed that real knowledge of things is impossible.
Eurosceptics are citizens or politicians who present themselves as ‘sceptical’ - critical - of the union which they say takes powers away from their national government and poses a threat to their national sovereignty.
There are supposedly two forms of euroscepticism: ‘hard’ and ‘soft’.
‘Hard’ or ‘withdrawalist’ euroscepticism is the opposition to membership or the existence of the EU. The European Parliament’s Europe of Freedom and Democracy group, which includes the United Kingdom Independence Party (UKIP), is hard eurosceptic.
‘Soft’ or ‘reformist’ euroscepticism supports the existence of the EU and membership to the Union, but opposes further integrationist EU policies and the idea of a federal Europe. The European Conservatives and Reformists group, including the British Conservative Party and the European United Left-Nordic Green Left alliance, can be described as soft eurosceptics.
But euroscepticism can further be viewed as part of a spectrum, ranging from 'europhobia' - similar to xenophobia - to a healthy sceptical attitude, and questioning of accepted beliefs. As such, certain forms of scepticism exist across all political spheres.
Interviewees from a December 2011 European Parliament report on British euroscepticism, ranging from a former EU Council press officer to a correspondent from the Daily Express, a particularly eurosceptic UK paper, outlined such a spectrum. Xenophobia and europhobia were judged to be the most extreme expression of euroscepticism. 'Non-integrationism', 'eurorealism', 'populism', 'euroboredom' and criticism of the EU were deemed milder forms.
Michael Shermer, editor of Skeptic magazine, says scepticism is a process of discovering the truth rather than a blanket non-acceptance of the latest theory. Hence, unthinking support can be as bad, if not worse, than blanket non-acceptance. This is why both eurosceptics and supporters of the EU both try to claim they are 'realistic'.
This information is taken from this link.